1. Field
This disclosure relates to a unit cell of honeycomb-type solid oxide fuel cell, a stack using the unit cell and methods for manufacturing the unit cell and the stack.
2. Description of the Related Art
In general, solid oxide fuel cells (SOFCs) may be classified into cylindrical SOFCs and planar SOFCs according to the shape of unit cells.
In case of a cylindrical SOFC, gas sealing may not be required but a high-cost process such as electrochemical vapor deposition (EVD) may be required. A cylindrical SOFC may have a large internal resistance due to a long current collection distance between both electrodes. In addition, due to a long distance from a reactive site to a collector, it may be difficult to obtain a high output density from a cylindrical SOFC as compared to a planar SOFC.
On the contrary, a planar SOFC can provide high cost efficiency due to the use of a wet process and show a short current collection distance. However, it may be difficult to perform gas sealing in a planar SOFC. A planar SOFC can provide a high internal resistance in a stack due to the non-uniformity in thickness from one unit cell to another unit cell.
Therefore, various types of SOFC unit cells and stack structures have been developed to overcome the above-mentioned shortcomings of cylindrical or planar SOFCs, to improve quality of SOFCs, and to downsize SOFCs.
Typical examples of such SOFCs may include anode-supported SOFCs or honeycomb-type SOFCs that enables thinning of electrolytes up to 10 μm or less.